# WorksheetFunction.BetaInv Method (Excel)

Office 2013

Returns the inverse of the cumulative distribution function for a specified beta distribution. That is, if probability = BetaDist(x,...), then BetaInv(probability,...) = x.

Important

This function has been replaced with one or more new functions that may provide improved accuracy and whose names better reflect their usage. This function is still available for compatibility with earlier versions of Excel. However, if backward compatibility is not required, you should consider using the new functions from now on, because they more accurately describe their functionality.

## Syntax

expression .BetaInv(Arg1, Arg2, Arg3, Arg4, Arg5)

expression A variable that represents a WorksheetFunction object.

### Parameters

Name

Required/Optional

Data Type

Description

Arg1

Required

Double

A probability associated with the beta distribution.

Arg2

Required

Double

The Alpha parameter of the distribution.

Arg3

Required

Double

The Beta parameter the distribution.

Arg4

Optional

Variant

An optional lower bound to the interval of x.

Arg5

Optional

Variant

An optional upper bound to the interval of x.

Double

## Remarks

The beta distribution can be used in project planning to model probable completion times given an expected completion time and variability.

• If any argument is nonnumeric, BetaInv generates an error value.

• If alpha ≤ 0 or beta ≤ 0, BetaInv generates an error value.

• If probability ≤ 0 or probability > 1, BetaInv generates an error value.

• If you omit values for A and B, BetaInv uses the standard cumulative beta distribution, so that A = 0 and B = 1.

Given a value for probability, BetaInv seeks that value x such that BetaDist(x, alpha, beta, A, B) = probability. Thus, precision of BetaInv depends on precision of BetaDist. BetaInv uses an iterative search technique. If the search has not converged after 100 iterations, the function generates an error value.